The age thing will cut down on opportunities, but not eliminate them.
The no savings is a problem. For one thing, you will be paid monthly, and you have to be able to eat and live until that first pay arrives. I knew a couple of people who arrived with very little money, and they were able to get a month's salary advanced to them. Some companies have apartments they keep in their name and rent to employees, which would save you the large deposit and key money requirements for getting a place to live. You'll be better off financially if you avoid the really big cities, like Tokyo/Yokohama and Osaka.
It used to be common for people to go to Japan, save lots of money, and pay off debts. I don't know if that is possible anymore. Any time anyone mentions debt, the response is always "Korea'. If you must make substantial monthly payments on the debt, it may well be impossible for you to have enough money to live.
Then there is airfare. That may not be provided by the employer, even if you are hired from abroad.
Look at some general websites:
Dave's ESL Cafe , which is the primary ESL website, and maybe
TEFLDaddy. The guy who runs TEFLDaddy lived and worked in Korea and other Asian countries for years. Look at the articles, read the forums, post a question or two. That will give you a better idea of whether this will work out for you.
If you want to try teaching in a country that won't require so much in startup costs, look at China and other countries where the employer will pay airfare.
Even back in the early 90's, I knew unmarried couples living together and teaching English. However, if you were to marry, if one of you got a job the other would get a spouse visa, which would allow you to work. Once you have that it would be easier to find a job because you would have the advantage of being a cheaper employeed than one that requires a visa. One of the problems in looking for a job is that you get to compete against all those WHV people.
I hope you can work everything out!